Breithauptite, nickel antimonide, an uncommon ore mineral

--- Cobalt silver district, northeast Ontario, Canada

Figure 1.
A small angular piece of high-grade ore, composed largely of
the colourful nickel antimonide, breithauptite (NiSb)
with white calcite, evidently a
relatively low-temperature hydrothermal mineralization.
This sample, from Roger Poulin (Roger's Minerals, Val Caron, Ontario)
is from the Nipissing 73 mine, Coleman Township,
in the Cobalt mining district of the Temiskaming region,
a famed silver camp of the early 20th century.
Thin-section chip 2929, main sample 2930.

"Rock of the Month #184, posted for October 2016" ---

Breithauptite

is an ore mineral seldom encountered in hand specimen, or indeed under the
microscope. The ideal formula is a simple antimonide, NiSb,
corresponding
to 32.5 wt.% Ni and 67.5 wt.% Sb. This dense, lustrous ore mineral may incorporate
lesser amounts of other valuable elements into its crystal lattice, an example being palladium
(Cabri, 1992).
This mineral is very dense (specific gravity of pure material circa 8.23),
and though the crystal symmetry is hexagonal, the
material most often appears massive to reniform in hand specimen.

Occurrence

Discovery of rich silver veins in the Cobalt district of Ontario led
to a long history of continuous silver
production from 1903 to 1989.
Research on the ores gave rise to
descriptions of veins of unusually complex mineralogy and
ore textures (e.g., Miller, 1913; Bastin, 1917: see also
"Rock of the Month 40, arsenide ore").
The mineral listing includes, besides native silver, native bismuth and
a horder of other minerals, such as sulphides and sulphosalts, arsenides and antimonides.
The ore minerals include
smaltite, niccolite, breithauptite and chloanthite,
erythrite and other secondary salts,
cobaltite, arsenopyrite, dyscrasite and pyrargyrite.
The gangue (waste) minerals are dominated by calcite and dolomite.
The Cobalt-Gowganda area is noted for complex Ag ores
with diverse Ni- Co- As- Sb- S mineral species
(Petruk et al., 1971). Notable minerals include
niccolite
(nickeline, NiAs, with up to 6.5 wt.% Sb,
3.9% Co and 0.7% Fe),
diarsenides such as
safflorite, which is the most common arsenide in the ores of the region,
and
triarsenides such as skutterudite, which is found in all the
arsenide assemblages.
A valuable, recent compilation, with illustrations of fine specimens,
is given by Joyce et al. (2012),
and much of the material is in the collections of the
Royal Ontario Museum in Toronto.

Breithauptite is reported as a minor component of a number of ore deposits,
which contain variable proportions of
silver, gold and base metals.
These include Ni-Cu-PGE deposits, sediment-hosted base-metal and
manganese deposits, and even a large alkaline igneous complex.
A new treasury of ore mineral species and textures,
including many examples from Argentina,
includes niccolite
and
breithauptite
(Paar et al., 2016).
The mineral appears in a number of reviews of localities
(e.g., Bernard and Hyrsl, 2015).
A partial listing of occurrences is as follows:

Sulitjelma, Norway

Bergslagen, Sweden

Vammala, Finland

The Shetland ophiolites, northern Scotland

Leadhills district, Southern Uplands, Scotland (Chapman et al., 2000)

Andreasberg, Harz, Germany

El Molar deposit, Spain

Sarrabus, Sardinia, Italy

Ilimaussaq complex, southwest Greenland

Wellgreen deposit, Yukon, Canada

Tulameen district, British Columbia, Canada

MacLellan gold deposit, Lynn Lake, Manitoba, Canada

Cobalt silver camp, Ontario, Canada

Raglan belt, northern Quebec, Canada

Voisey's Bay deposit, Labrador, Canada

Aguilar mine, Jujuy, Argentina

Rajasthan, northwest India

Kolar gold field, south India

Some unusual hydrothermal occurrences are also reported.
Ore minerals (in the normal heavy-metal context)
are rare in the Ilimaussaq peralkaline intrusion,
in the Gardar province along the western coast of south Greenland.
Arsenides and antimonides are part of
a late, relatively low-temperature paragenesis,
including
galena, skutterudite, breithauptite, niccolite, maucherite,
loellingite and gudmundite
(Soen and Sorensen, 1964). More typical are
remobilizations of existing metallic ores.
At the Sulitjelma massive sulphide deposit
in Norway,
two Au and Sb mineral parageneses occur in coarse segregations related to late
remobilization of part of the sulphide mass. The associations,
deposited from S-poor fluids at <300°C, are
(a) galena, freibergite, gudmundite, aurostibite and
electrum, and (b) breithauptite, gudmundite, electrum, galena and
pyrrhotite (Cook, 1992).
At the large, metamorphosed
Rampura-Agucha sedex Pb-Zn deposit in Rajasthan,
rare
minerals include native Sb and breithauptite
(Gandhi, 2003: Pal and Deb, 2009).
NiSb is one of a number of Ni-Sb-Te minerals that form
under specific conditions at
relatively low temperatures
(Laufek et al., 2010).

Breithauptite is often found with base-metal sulphides such as galena (PbS),
with arsenides and silver minerals.
It seems to be most abundant in veins and other concentrations of
remobilized sulphides. Such remobilization may be induced by regional metamorphism, or
by sequential intrusion of batches of magma.
The resulting hydrothesrmal assemblages evidently form at
modest temperatures, <450°C to <300°C.

Historical Notes

The Freiberg Mining Academy began supplying students with
mineral specimens in 1765 (Wilson and Neumeier, 2015).
Famous geoscientists who worked there
include Abraham Gottlob Werner, Wilhelm Maucher, and the man in whose
honour breithauptite was named,
Johann Friedrich August Breithaupt (1791-1873).
Breithaupt was a mineralogist and a professor
at the Freiberg Mining Academy in Saxony.
He studied under Werner and succeeded
Mohs as professor of mineralogy.
He is credited with the discovery of 47 valid
mineral species, and with the development
of the concept of paragenesis (the chronological evolution
of mineral assemblages, especially in ore deposits).
The modern breadth of the
Freiberg Mineralogical Collection
is very impressive.

Technical Note

NiSb is an electrical conductor,
somewhat like native metals (copper, silver, iron...)
and the ferrosilicon class of industrial alloys.
The good electrical conductivity (σ, measured in Siemens/m)
in these minerals and alloys
defeats simple measurement of bulk
magnetic susceptibility
using a coil-based meter like the SM-30
(the apparent, erroneous, answer, as with
ferrosilicon or native copper, is
always a large negative number).
Metals, and graphite (parallel to cleavage planes)
are good conductors, with low electrical resistivity, whereas
typical ore minerals (common sulphides) are not.
As a bonus, minerals such as copper, silver and breithauptite,
as well as iron meteorites, may all be
found using metal detectors.
Approximate resistivity values (ρ, the inverse of conductivity, and
measured in ohm-metres) for a few metals and
other ore minerals
(Keller, 1987) are as follows:

Chapman,RJ, Leake,RC, Moles,NR, Earls,G, Cooper,C, Harrington,K
and Berzins,R (2000)
The application of microchemical analysis of alluvial gold grains to the
understanding of complex local and regional gold mineralization: a case
study in the Irish and Scottish Caledonides.
Econ.Geol. 95, 1753-1773.